Download Media Player Classic

Media Player Classic will sparse almost any container (file type) - MPEG, AVI (even truncated ones), QuickTime (MOV), MP4, 3GP, Real Media (RM, RMVB), ASF/WMV, OGM, MKV.
The player only has built-in codecs for MPEG-2/DVD, and AC3 though (perhaps a few others). It will rely on system-wide codecs, or in the case of Real and QuickTime, codecs installed in the Real and QuickTime program folders, for playback of video and audio streams encoded in specific codecs.

updates:
MPC has, for instance, a built in DVD player with real-time zoom, support for AVI subtitles, QuickTime and RealVideo support (requires QT and/or Real player), and lots more.